1. Field of the Invention
The present invention relates to anti-seize and/or lubricant compositions, particularly compositions including nano-sized particles.
2. Brief Description of Related Technology
An anti-seize composition is typically used to prevent metal-to-metal joints from seizing, galling or cold-welding. Seizing may occur when metal-to-metal joints are placed under fairly high loads and then subjected to reciprocal, relatively small-displacement movements. A lubricating composition is typically used to reduce the coefficient of friction between two sliding parts, thereby facilitating relatively large sliding movements between the parts. An anti-seize/lubricating composition, depending upon the specific application, may be used as an anti-seize composition, as a lubricating composition, or in both capacities. For example, an anti-seize/lubricating composition may act as a lubricating composition for a lightly loaded roller bearing. An anti-seize/lubricating composition may acts as an anti-seize composition with applied to a highly loaded threaded fastener subjected to load reversals. An anti-seize/lubricating composition may act in both capacities when parts, for example, gears, need to slide relative to one another when rotating and to transmit high loads when stationary. Anti-seize/lubricating compositions are available as liquids, pastes, solids and aerosols.
Anti-seize/lubricating compositions may be expected to operate under a variety of conditions, including, for instance, high loads, extreme temperatures, dirty and/or corrosive operating environments, etc. In addition, anti-seize/lubricating compositions may be expected to survive, for example, by not wearing off or by not breaking down, for relatively extended periods of time. Furthermore, anti-seize/lubricating compositions may be expected to operate without contaminating adjacent parts cause by, for example, simple physical transference or outgassing of volatile components. Anti-seize/lubricating compositions may also be expected to protect the surface of the individual parts, for example, by inhibiting or preventing corrosion. Additionally, anti-seize/lubricating compositions may be expected to have other, more esoteric characteristics, such as facilitating heat transfer, being non-toxic, working under extreme humidity conditions, etc.
Henkel Corporation manufactures and sells many anti-seize/lubricant compositions. For instance, C5-A Copper Anti-Seize is a suspension of copper and graphite in a high-quality grease, which protects metal parts from rust, corrosion, galling, and seizing at temperatures to 1800° F. (982° C.), and tested to MIL(PRF)-A-907-E. Nickel Anti-Seize is a copper-free product, recommended for stainless steel and other metal fittings to prevent corrosion, seizing, and galling in harsh, chemical environments, and temperatures to 2400° F. (1315° C.). Moly Paste is a low friction product, which lubricates press fits, protects during break-in and under high static loads up to 750° F. (400° C.). Silver Grade Anti-Seize is a temperature-resistant, petroleum-based inert lubricant compound fortified with graphite and metallic flake, which will not evaporate or harden in extreme cold or heat and is for use in assemblies up to 1600° F. (871° C.). Heavy Duty Anti-Seize is a metal free product, which provides excellent lubricity, outstanding lubrication to all metals including stainless steel, aluminum, and soft metals up to 2400° F. (1315° C.) Marine Grade Anti-Seize is formulated to protect assemblies exposed directly or indirectly to fresh and salt water. Marine Grade Anti-Seize works well in high humidity conditions, and has excellent lubricity, superior water wash-out and water spray resistance, and prevents galvanic corrosion, protects in temperatures from −29° C. to 1315° C. (−20° F. to 2400° F.). Graphite-50 Anti-Seize is an electrically conductive, non-metallic product, which is temperature resistant up to 900° F. (482° C.). Moly-50 Anti-Seize is a thread lubricant, which is temperature resistant to 750° F. (400° C.) and provides excellent lubricity. Zinc Anti-Seize protects aluminum and ferrous surfaces from seizure and corrosion up to 750° F. (400° C.). Food Grade Anti-Seize prevents seizure, galling, and reduces friction of stainless steel and other metal parts up to 750° F. (400° C.). N-1000 High Purity Anti-Seize is a copper-based product, which is suitable for long-term, stainless steel applications and high-nickel, alloy bolting. N-5000 High Purity Anti-Seize is a nickel-based product is recommended for highly corrosive environments to 2400° F. (1315° C.). High Performance N-5000 High Purity Anti-Seize, a nickel-based product, is temperature resistant to 2400° F. (1315° C.). N-7000 High Purity Anti-Seize is a metal-free product, which provides high levels of purity. White Hi-Temp Anti-Seize is a non-metallic product which protects against high temperature seizing and galling of mated metal parts, up to 2000° F. (1093° C.), while demonstrating excellent lubricity and use on various metals, such as copper, brass, cast iron, steel and all alloys including stainless steel.
None of these known anti-seize/lubricating compositions include nano-sized lubricating solid particles. A nano-sized particle is a microscopic particle whose size is measure in nanometers (nm), generally with at least one dimension being less than 500 nm. Nano-sized particles typically exhibit properties different from the properties of the bulk material or the material in a particle size larger than nano-size. One explanation for this is that as particles decrease in size surface characteristics of the material begin to dominate, possibly because the percentage of atoms at the surface becomes significant.
Nano-sized particles may be made from a wide variety of materials, including, by way of non-limiting example, carbon, metals, and ceramics. Carbon black is an example of a nano-sized particle that has been used for many years. Nanotubes made of carbon, boron and nitrogen are known. Pure metal nano-sized particles, such as silver or platinum find used as catalysts. Ceramics may include metal oxides, such as titanium, zinc, aluminum and iron oxides, or silicates or silicon oxides, such as day. In addition, nano-sized particles may be formed of one or more materials. For example, nano-sized particles may be coated or chemically modified to make them more or less hydrophilic, or nano-sized particles may be doped, i.e., a dopant element such as boron, phosphorous, and arsenic, to name a few, may be incorporated into the base material.
Nano-sized particles may be formed using a wide variety of techniques, including, by way of non-limiting examples, chemical or physical vapor deposition, physical vapor synthesis, reactive sputtering, electro-deposition, laser pyrolysis, laser ablation, spray conversion, mechanical alloying, sol gel techniques, supercritical fluid precipitation and solid-state processes such as grinding or milling.
Nano-sized particles may come in a wide variety of forms, including, by way of non-limiting example, powders, crystals, flakes, nanotubes, nanowires, nanospheres. Nano-sized particles may be nano-sized in all three dimensions, in two dimensions, or only in one dimension. Thus, for example, metal oxide ceramic nano-sized powders may be roughly the same size (ranging from 2-3 nm up to 200-300 nm) in all three dimensions. Silicate nano-sized particles may form flakes having a thickness on the order of 1 nm and width dimensions on the order of 100-1000 nm. And carbon nanotubes, multi-walled or single walled, may have diameters on the order of 0.5-50 nm, but with lengths ranging from a few hundred nanometers to a micron or more.
Conventional lubricants typically have relatively low percentages of lubricating solids (on the order of 5-10%). Under extreme pressure conditions, the lubricating solids may squeeze out from between the working parts, allowing detrimental metal-to-metal contact. Alternatively, at elevated temperatures (on the order of 300-600° F.), the oil or grease may burn off, leaving only the lubricating solids to act as a barrier between the working parts. Under these conditions, lubricants having relatively low percentages of lubricating solids may also allow detrimental metal-to-metal contact.
Despite the state of the technology, no anti-seize and/or lubricating compositions have been described or placed on the market with nano-sized lubricating solid particles. There is however a need for anti-seize and/or lubricating compositions formulated with nano-sized lubricating solid particles to take advantage of the unique surface-driven characteristics of the nano-sized particles.